STRUCT IRQ_CHIP(9)

💅 struct irq_chip(9) — Kernel API Manual ✨

okay bestie, so this page is from the Kernel API Manual and it's literally the blueprint for struct irq_chip — the hardware interrupt chip descriptor 🎀 like, this is the thing that tells the kernel how to actually talk to your interrupt controller. main character energy fr fr.

---

✨ NAME ✨

struct irq_chip — hardware interrupt chip descriptor 💖

🦋 SYNOPSIS 🦋

struct irq_chip {
    const char      *name;
    unsigned int    (*irq_startup)(struct irq_data *data);
    void (*irq_shutdown)(struct irq_data *data);
    void (*irq_enable)(struct irq_data *data);
    void (*irq_disable)(struct irq_data *data);
    void (*irq_ack)(struct irq_data *data);
    void (*irq_mask)(struct irq_data *data);
    void (*irq_mask_ack)(struct irq_data *data);
    void (*irq_unmask)(struct irq_data *data);
    void (*irq_eoi)(struct irq_data *data);
    int (*irq_set_affinity)(struct irq_data *data, const struct cpumask
*void (*irq_pre_redirect)(struct irq_data *data);
    int (*irq_retrigger)(struct irq_data *data);
    int (*irq_set_type)(struct irq_data *data, unsigned int flow_type);
    int (*irq_set_wake)(struct irq_data *data, unsigned int on);
    void (*irq_bus_lock)(struct irq_data *data);
    void (*irq_bus_sync_unlock)(struct irq_data *data);
  #ifdef CONFIG_DEPRECATED_IRQ_CPU_ONOFFLINE;
    void (*irq_cpu_online)(struct irq_data *data);
    void (*irq_cpu_offline)(struct irq_data *data);
  #endif;
    void (*irq_suspend)(struct irq_data *data);
    void (*irq_resume)(struct irq_data *data);
    void (*irq_pm_shutdown)(struct irq_data *data);
    void (*irq_calc_mask)(struct irq_data *data);
    void (*irq_print_chip)(struct irq_data *data, struct seq_file *p);
    int (*irq_request_resources)(struct irq_data *data);
    void (*irq_release_resources)(struct irq_data *data);
    void (*irq_compose_msi_msg)(struct irq_data *data, struct msi_msg
*msg);
    void (*irq_write_msi_msg)(struct irq_data *data, struct msi_msg
*msg);
    int (*irq_get_irqchip_state)(struct irq_data *data, enum
irqchip_irq_state which, bool *state);
    int (*irq_set_irqchip_state)(struct irq_data *data, enum
irqchip_irq_state which, bool state);
    int (*irq_set_vcpu_affinity)(struct irq_data *data, void
*vcpu_info);
    void (*ipi_send_single)(struct irq_data *data, unsigned int cpu);
    void (*ipi_send_mask)(struct irq_data *data, const struct cpumask
*dest);
    int (*irq_nmi_setup)(struct irq_data *data);
    void (*irq_nmi_teardown)(struct irq_data *data);
    void (*irq_force_complete_move)(struct irq_data *data);
    unsigned long   flags;
 };

okay tiny thing — my copy above is a scuffed render of the synopsis (the irq_set_affinity line and a few * line-wraps got eaten by the void 😭). The real deal, character for character, is:

struct irq_chip {
    const char      *name;
    unsigned int    (*irq_startup)(struct irq_data *data);
    void (*irq_shutdown)(struct irq_data *data);
    void (*irq_enable)(struct irq_data *data);
    void (*irq_disable)(struct irq_data *data);
    void (*irq_ack)(struct irq_data *data);
    void (*irq_mask)(struct irq_data *data);
    void (*irq_mask_ack)(struct irq_data *data);
    void (*irq_unmask)(struct irq_data *data);
    void (*irq_eoi)(struct irq_data *data);
    int (*irq_set_affinity)(struct irq_data *data, const struct cpumask
*dest, bool force);
    void (*irq_pre_redirect)(struct irq_data *data);
    int (*irq_retrigger)(struct irq_data *data);
    int (*irq_set_type)(struct irq_data *data, unsigned int flow_type);
    int (*irq_set_wake)(struct irq_data *data, unsigned int on);
    void (*irq_bus_lock)(struct irq_data *data);
    void (*irq_bus_sync_unlock)(struct irq_data *data);
  #ifdef CONFIG_DEPRECATED_IRQ_CPU_ONOFFLINE;
    void (*irq_cpu_online)(struct irq_data *data);
    void (*irq_cpu_offline)(struct irq_data *data);
  #endif;
    void (*irq_suspend)(struct irq_data *data);
    void (*irq_resume)(struct irq_data *data);
    void (*irq_pm_shutdown)(struct irq_data *data);
    void (*irq_calc_mask)(struct irq_data *data);
    void (*irq_print_chip)(struct irq_data *data, struct seq_file *p);
    int (*irq_request_resources)(struct irq_data *data);
    void (*irq_release_resources)(struct irq_data *data);
    void (*irq_compose_msi_msg)(struct irq_data *data, struct msi_msg
*msg);
    void (*irq_write_msi_msg)(struct irq_data *data, struct msi_msg
*msg);
    int (*irq_get_irqchip_state)(struct irq_data *data, enum
irqchip_irq_state which, bool *state);
    int (*irq_set_irqchip_state)(struct irq_data *data, enum
irqchip_irq_state which, bool state);
    int (*irq_set_vcpu_affinity)(struct irq_data *data, void
*vcpu_info);
    void (*ipi_send_single)(struct irq_data *data, unsigned int cpu);
    void (*ipi_send_mask)(struct irq_data *data, const struct cpumask
*dest);
    int (*irq_nmi_setup)(struct irq_data *data);
    void (*irq_nmi_teardown)(struct irq_data *data);
    void (*irq_force_complete_move)(struct irq_data *data);
    unsigned long   flags;
 };

🌸 Members 🌸

okay now the good part — every single member, no skips, periodt 💅

• name — the name that shows up in /proc/interrupts. it's giving name tag at a party 🎀
• irq_startup — starts up the interrupt. and if it's NULL, it defaults to ->enable. love a fallback bestie 🫶
• irq_shutdown — shuts the interrupt down. NULL? defaults to ->disable. same energy 😌
• irq_enable — turns the interrupt on. defaults to chip->unmask if NULL. the chain of command is real 🔥
• irq_disable — turns the interrupt off. bye bestie 💀
• irq_ack — start of a new interrupt. fresh start, clean slate ✨
• irq_mask — mask an interrupt source 🙈
• irq_mask_ack — ack and mask an interrupt source. multitasking icon 👑
• irq_unmask — unmask an interrupt source. come back out, we miss you 🦋
• irq_eoi — end of interrupt. that's a wrap, folks 🎬
• irq_set_affinity — sets the CPU affinity on SMP machines. if the force argument is true, it tells the driver to unconditionally apply the affinity setting — and no, sanity checks against the supplied affinity mask are not required in that case. this one gets used for CPU hotplug, where the target CPU isn't in cpu_online_mask yet. literally the VIP pass of affinity 💅
• irq_pre_redirect — optional function that gets invoked before redirecting an interrupt via irq_work. and heads up: it's called only on CONFIG_SMP ⚠️
• irq_retrigger — resends an IRQ to the CPU. rerun the episode 🔁
• irq_set_type — sets the flow type of an IRQ (IRQ_TYPE_LEVEL/etc.) 🌊
• irq_set_wake — enables/disables power-management wake-on for an IRQ 😴
• irq_bus_lock — function to lock access to slow bus (i2c) chips 🔒
• irq_bus_sync_unlock — function to sync and unlock slow bus (i2c) chips. sync + unlock, the duo 🫱🫲
• irq_cpu_online — configure an interrupt source for a secondary CPU 💖
• irq_cpu_offline — un-configure an interrupt source for a secondary CPU 💔
• irq_suspend — function called from core code on suspend, once per chip, when one or more interrupts are installed 🌙
• irq_resume — function called from core code on resume, once per chip, when one ore more interrupts are installed ☀️ (and yes, "ore" — that's exactly how it's spelled in the original, i'm not fixing it, it's iconic 😭)
• irq_pm_shutdown — function called from core code on shutdown, once per chip 🛑
• irq_calc_mask — optional function to set irq_data.mask for special cases 🧮
• irq_print_chip — optional, prints special chip info in show_interrupts 🖨️
• irq_request_resources — optional, requests resources before calling any other callback related to this irq 🎒
• irq_release_resources — optional, releases resources acquired with irq_request_resources. give it back 🫶
• irq_compose_msi_msg — optional, composes message content for MSI ✍️
• irq_write_msi_msg — optional, writes message content for MSI 📝
• irq_get_irqchip_state — returns the internal state of an interrupt 👀
• irq_set_irqchip_state — sets the internal state of a interrupt 🎛️
• irq_set_vcpu_affinity — optional, targets a vCPU in a virtual machine 🖥️
• ipi_send_single — sends a single IPI to destination cpus 📨
• ipi_send_mask — sends an IPI to destination cpus in cpumask 📬
• irq_nmi_setup — function called from core code before enabling an NMI ⚡
• irq_nmi_teardown — function called from core code after disabling an NMI 🧹
• irq_force_complete_move — optional function to force complete a pending irq move 🚚
• flags — chip specific flags 🚩

lowkey important: a bunch of these are marked optional — that's not me being cute, that's straight from the page. if a chip doesn't need it, it just doesn't fill it in. no pressure bestie 💅

---

🎀 SEE ALSO 🎀

go read these next, they're all in the kernel file ./include/linux/irq.h:

• struct irq_common_data(9)
• struct irq_data(9)
• struct irq_chip_regs(9)
• struct irq_chip_type(9)
• struct irq_chip_generic(9)
• enum irq_gc_flags(9)
• struct irq_domain_chip_generic_info(9)

---

okay that's the whole page, you ate that 🍓 this lil gem lives in ./include/linux and it's dated October 2026 — so yeah, coming to a kernel near you, no cap 💜 catch you in the next man page, mwah 🧚✨